Apparatus for superimposing character patterns in accordance with dot-matrix on video signals

ABSTRACT

An apparatus for superimposing an image represented in a predetermined dot arrangement on a video signal. The apparatus includes an inputting device, a memory, a storage block selecting device and a signal switching circuit. The memory has an arrangement of a plurality of storage blocks, each of which includes an arrangement of a plurality of unit storage cells each for storing one bit. The inputting device inputs externally prepared binary signals. The storage block selecting device selects a predetermined storage block for every inputted bit information. All the unit storage cells in the selected storage block store the inputted bit information. The signal switching device sequentially reads the contents stored in each unit storage cell in synchronization with a video signal, switches the video signal and a predetermined superimposing video signal to each other in accordance with the contents and outputs the same. As a result, each dot represented by a plurality of dots in the reproduced video signal after being superimposed. The signal represented by the inputted binary information is reproduced on a picture frame as an expanded image.

BACKGROUND OF THE PRESENT INVENTION

1. Field of the Present Invention

The present invention relates generally to apparatus for superimposing asignal on another signal, and more particularly, to an apparatus used invideo equipments to overlay external information on a video signal.

2. Description of the Related Art

Apparatus for interposing information such as titles on a picture havebeen used in built-in-camera VTR (Video Tape Recorder) and the like.FIG. 1 is a block diagram showing a typical example of a conventionalapparatus of this kind. Referring to FIG. 1, the conventional apparatusincludes an A/D (Analog/Digital) converter 12 which from a terminal 10receives a luminance signal (hereinafter referred to as Y signal) suchas a video signal produced by a video camera or reproduced by a VTR todigitize the same based on a certain signal level and converts the sameinto digital serial data; a shift register 16 connected to the A/Dconverter 12 and a terminal 14 for converting the serial data andparallel data, for example, of 8 bits into each other in synchronizationwith a clock signal supplied from the terminal 14; a timing generator 22connected to the terminals 14, 18 and 20 for generating an addresssignal showing a position on an image of a portion being processed ofthe video signal, and in accordance with the processing mode, generatinga signal indicating operation timing for elements included in thesuperimposing apparatus in response to a horizontal synchronizing signalH_(D) and a vertical synchronizing signal V_(D) of the video signalinputted from the terminals 18 and 20; a memorv 24 connected to theshift register 16 and the timing generator 22 for storing the paralleldata converted by the shift register 16 in the address selected by theaddress signal from the timing generator 22 and for outputting thestored contents of the address selected by the address signal from thetiming generator 22 to the shift register 16; a color synthesis circuit26 connected to the shift register 16 for outputting a component signalfor different colors of RGB (Red-Green-Blue) for displaying the title inmulti-color in response to a signal which is read out from the memory 24and converted into the serial data by the shift register 16, inaccordance with the colors specified by a controller (not shown) or thelike; and a display circuit 32 for mixing each of the component signalsof RGB and a video signal inputted from a terminal 28 to be superimposedand outputting the mixed signals to an output terminal 30.

Each of the signals produced by the timing generator 22 includes awriting control signal WE for controlling a timing of writing the datato the memory 24 and a reading control signal OE for controlling atiming of reading the data from the memory 24.

The display circuit 32 includes a matrix circuit for synthesizing, forexample, a Y signal and color difference signals of the title from thecomponent signal; a circuit for producing a luminance blanking signaland a chroma blanking signal showing a timing of switching between the Yand the color signals of the title and those of the picture to besuperimposed respectively; and a switching circuit responsive to theblanking signal for switching between the signal of the title and thesignal of the picture at a high speed.

Referring to FIG. 1, an operation of a conventional superimposingapparatus will be described. The apparatus has two operation modes. Thefirst is a title-image storing mode for reading a title image andstoring the same into the memory 24. The second mode is a superimposingmode for overlaying the title stored in the memory 24 on a video signalinputted from the terminal 28. The modes are switched to each other byan operator by means of an operation panel (not shown).

In the title-image storing mode, a Y signal of a video signal showing atitle taken by a camera is inputted from the terminal 10. Inputting thetitle is carried out by, for example, hand-writing the title on a whitepaper and converting the title into video signals by a video-camera orthe like. The A/D converter 12 compares a level of the Y signal with agiven level of a reference signal to convert the Y signal into thedigital data by outputting a value of "0" when the level of the Y signalis higher than that of the reference signal and otherwise outputting avalue of "1".

The digital data is inputted to the shift register 16. The shiftregister 16 shifts and stores 8 bits of the serial data at a time andoutputs the same as the parallel data of 8 bits to the memory 24. H_(D)and V_(D), inputted to the timing generator 22, synchronize with the Ysignal inputted from the terminal 10. The synchronization is carried outby extracting only a sync signal from the video signal outputted from avideo camera taking a title and amplifying the same.

The timing generator 22 outputs a signal showing a vertical andhorizontal positions of the Y signal being processed on the pictureframe in response to the clock, H_(D) and V_(D). The signal indicates anaddress in which the data is stored in the memory 24.

When storing all the data of the title image inputted from the terminal10 in the memory 24 is finished, a hand-written title image is stored inthe memory 24 as the image represented by two different values eachrepresenting a background portion and a title portion, respectively.

Now, the apparatus operates as follows when the title image stored inthe memory 24 is superimposed on a video signal inputted from theterminal 28.

A video signal taken by, for example, a video camera, or reproduced by aVTR is inputted from the terminal 28.

The horizontal synchronizing signal H_(D) and the vertical synchronizingsignal V_(D) of the video signal inputted from the terminal 28 areinputted to the terminals 18 and 20 respectively. The timing generator22 outputs an address signal representing a position of a pixel on thepicture frame and a OE signal indicating the timing of the reading fromthe memory 24 in response to the clock, H_(D) and V_(D). The contents ofthe address specified by the address signal are outputted to the shiftregister 16.

The shift register 16 converts the parallel data of 8 bits read out fromthe memory 24 into the 8-bit serial data by serially shifting andoutputting the same.

The color synthesis circuit 26 outputs a component signal of RGB fordisplaying a title in a color specified by the operator in response tothe serial data from the shift register 16.

The display circuit 32 mixes the above-described component signals andthe video signal from the terminal 28 and outputs the mixed signals tothe output terminal 30. On this occasion, the display circuit 32switches the blanking signals at a high speed in response to thosesignals such that an image of the title is outputted for the part wherethe title characters exist and video signals are outputted for the restof the part.

A signal outputted from the output terminal 30 is recorded on, forexample, a video tape. The recorded signal is reproduced by a hometelevision or the like.

For displaying the title stored in the memory 24, various functions areprovided such as improving fineness of the display, reversing the titlecharacter and the background, displaying the title in a desired color,so-called "wipe" for displaying and/or erasing the title from apredetermined position or in a plurality of directions, "scrolling" forparallel-transferring the entire title picture on the frame and thelike. In some cases, memories capable of storing the data of a pluralityof frames for the title characters are provided. In some cases, thetitles can be changed from one to another.

As described above, a conventional superimposing apparatus is veryconvenient which provides an easy and real video shooting and/or a videoediting. However, there still exist such problems to be solved as thefollowing.

Conventionally, a title picture is formed by hand-writing characters onpaper, a white board or the like and converting the same into videosignals. The title is represented by two different values with referenceto luminance levels of character or pattern portions and a background.If contrast of an object is not sufficient or the background portion isspotted, the title picture may not be reproduced satisfactorily. In manycases it results in reduced sharpness of an image of a characterprofile. In accordance with a conventional method, hand-writtencharacters can be inputted with relative ease. However, printingcharacters cannot be easily made a title. Even though some titles areused repeatedly, it is necessary to make a new one each time. Namely,the conventional apparatus has a problem in its operability and qualityof a superimposed picture.

SUMMARY OF THE PRESENT INVENTION

Therefore, one object of the present invention is to provide asuperimposing apparatus which can produce a superimposed video signalhaving a good picture quality.

Another aspect of the present invention is to provide a superimposingapparatus by which a superimposed video signal having a good picturequality can be obtained and which is operable with simple procedures.

Still another aspect of the present invention is to improve clearness ofcharacters superimposed on a video signal during reproduction.

An additional aspect of the present invention is to provide an apparatuswhich, externally supplied with digital signals representing characterpatterns, is capable of superimposing the character patterns such thatthe enlarged characters will be reproduced on the screen.

Still further aspect of the present invention is to provide asuperimposing apparatus which improves color reproduction of thesuperimposed characters.

A still further aspect of the present invention is to provide asuperimposing apparatus capable of sufficiently enlarging characters tobe superimposed at least in a horizontal scanning direction anddisplaying the enlarged characters such that the characters aredisplayed with an improved color reproduction.

Additional aspect of the present invention is to provide a superimposingapparatus capable of preventing undesired pictures from beingsuperimposed on a video signal.

The above-described aspects can be accomplished by a superimposingcircuit including an input device for inputting signals of two differentvalues having a first predetermined plurality of bit information put ina predetermined order and a memory having at least an arrangement of thefirst plurality of storage blocks. Each storage block includes anarrangement of a second plurality of unit storage cells each for storinga bit. The superimposing apparatus further includes a storage blockselecting device responsive to the inputted bit information forselecting one of the storage blocks in a predetermined order to storethe inputted bit information in all the unit storage cells in theselected storage block, and a signal switching circuit for reading thebit information stored in the unit storage cells in the predeterminedorder in synchronization with video signals, thereby selectivelyswitching between video signals and predetermined video signals to bemixed in response to the read bit information and outputting theselected signal.

According to a preferred embodiment of the present invention, eachstorage block includes a second plurality of unit storage cells arrangedso as to logically form a predetermined matrix.

According to a more preferred embodiment, each matrix is divided into athird plurality of rows arranged in a first predetermined direction,each row includes a fourth plurality of unit storage cells arranged in asecond direction intersecting the first direction.

A binary signal externally prepared for representing a predeterminedimage is inputted through the input device. The information of each bitincluded in the binary signal is stored in all the unit storage cells inone storage block of a memory selected by the storage block selectingdevice. The signal switching circuit sequentially reads the contentsstored in the unit storage cells in synchronization with the videosignal. The signal switching circuit switches between the video signalsand the video signals to be mixed, in accordance with the readinformation. Therefore, one dot of the prepared image is superimposed onthe video signal as a plurality of dots represented by the unit storagecells included in the storage block. On a reproduced picture, theoriginal image is displayed, being enlarged corresponding to the numberof unit storage cells included in one storage block. Therefore, a plainimage is obtained in the superimposed image when reproduced. Inaddition, the character image to be superimposed is prepared in anexternal and suitable apparatus. Accordingly, it is easy to prepare theimage to be superimposed. Moreover, characters superimposed on theobtained reproduced image are of good shape and the picture is notdeteriorated due to unnecessary dots or the like in the superimposedimage.

Namely, the apparatus can be provided which is operated with simpleprocedures and is capable of superimposing an image on a video signalwith a good picture quality.

According to another aspect of the present invention, an apparatus forsuperimposing a predetermined image on a video signal includes an inputdevice for inputting a first binary signal including a first amount ofinformation, an information amount increasing circuit for outputting asecond binary signal having a second amount of information larger thanthe first amount of the information from the first binary signal, amemory for storing the information included in the second binary signaland being capable of storing at least the second amount of theinformation, and a signal switching circuit for sequentially reading theinformation stored in the memory in synchronization with the videosignal, thereby switching between the video signal and a predeterminedvideo signal to be mixed, in response to the read information to outputeither of them.

According to a preferred embodiment, the information amount increasingcircuit includes an information duplicating circuit for duplicating theinformation of the first binary signal.

According to a more preferred embodiment, the information duplicatingcircuit includes a circuit for repeating information duplication whichreceives one of the information and successively outputs a plurality ofinformation having the same value as that of the received information.

According to the more preferred embodiment, the first binary signalincludes a unit signal having a third predetermined amount ofinformation corresponding to one horizontal scanning period of the videosignal and the information duplicating circuit further includes a unitsignal duplicating circuit for receiving each unit signal and outputtinga plurality of duplications of the units signal.

The superimposing apparatus according to the present invention includesthe above-described elements. The first binary signal including thefirst amount of information is converted into the second binary signalby the information increasing circuit. The second binary signal has thesecond amount of information larger than the first amount ofinformation. The second binary signal is stored in the memory. Thesignal switching circuit sequentially reads the contents stored in thememory in synchronization with the video signal and in response to avalue thereof, switches between the video signal and the video signalsto be mixed to output either of them.

One unit of the information corresponds to one dot on the reproducedpicture. The increase of the information leads to an increase in area ofimage to be superimposed on the picture frame, which allows a picture tobe more plain. With the information duplicating circuit being provided,the superimposed image is enlarged in a horizontal scanning linedirection on the reproduced picture. In addition, with the signal unitduplicating circuit being provided, the superimposed image is enlargedin a vertical direction on the reproduced picture. Accordingly, thesuperimposed image can be obtained by the first binary character patternenlarged, which allows the image to be more plain.

The foregoing and other objects, features, aspects and advantages of thepresent invention will become more apparent from the following detaileddescription of the present invention when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description given below and the accompanying drawings which aregiven by way of illustration only, and thus are not limitative of thepresent invention, and wherein:

FIG. 1 is a block diagram of a conventional superimposing apparatus;

FIG. 2 is a block diagram of a superimposing apparatus according to oneembodiment of the present invention;

FIG. 3 is a schematic diagram showing double-size expansion of a titlecharacter;

FIG. 4 is a block diagram of a superimposing apparatus according toanother embodiment of the present invention;

FIGS. 5A to 5C are schematic diagrams showing a double-size expansion ofthe title character and increase of a vertical line width of the titlecharacter.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 2 is a block diagram showing a schematic structure of asuperimposing apparatus 34 according to one embodiment of the presentinvention. Referring to FIG. 2, the apparatus differs from aconventional apparatus in that it includes a serial I/O (input/outputdevice) 38 for receiving externally prepared text font data representinga title character from an additional terminal 36 and a display dataconverting circuit 40 connected to the serial I/O 38, the shift register16 and the memory 24 for restructuring the character represented by thetext font data inputted from the serial I/O 38 to input to the shiftregister 16 the font data. The font data is converted in such a mannerthat the character is represented by a matrix containing doubled rowsand doubled columns each. The circuit 40 is also for calculating anaddress in which each dot contained in the converted text font data isstored and for inputting the same to the memory 24.

As an apparatus for supplying the text font data of a external title tothe terminal 36, most suitable are so-called electronic organizers,portable word processors and the like which are compact, portable andcapable of producing data including kanji characters easily. Ininputting the text font data in the superimposing apparatus, a dedicatedcable may be employed. Other methods such as using a card withincorporated memories can be employed.

The display data converting circuit 40 includes a MPU (Micro ProcessorUnit) for twice enlarging the text font data by processing each addressof the memory 24 and a ROM (Read Only Memory) in which programs to beexecuted in the MPU are written. The storage address for the inputtedtext font data can be easily calculated by searching an addresscalculating table which is previously written in the ROM.

Referring to FIG. 2, an operation of the superimposing apparatus will bedescribed. There are three modes for superimposing operation of theapparatus. The first mode is a first title-image storing mode forstoring the title image inputted by a camera or the like in the memory24 as in the conventional one. A second mode is newly provided in theapparatus of the present invention. The second mode is a secondtitle-image storing mode in which the apparatus receives from theterminal 36 the digital text font data representing title charactersprepared by other apparatus and stores the same in the memory 24. Thethird mode is a conventional superimposing mode in which the title imagestored in the memory 24 and the video signal inputted from the terminal28 are overlaid to be outputted from the output terminal 30 as theconventional one.

The operations of the apparatus in the first title-image storing modeand the superimposing mode are the same as those of the conventionalapparatus in the title-image storing mode and the superimposing mode,respectively. Accordingly, description thereof will not be repeated hereand a description will be given only on the second image-title storingmode in the following.

The second title-image storing mode is implemented by selection of thesecond title-image storing mode by an operator using an operationalpanel (not shown). In this mode, there exists no input signal from theterminal 10. In addition, the address of the memory 24 is designated notby the timing generator 22 but by the display data converting circuit40.

To the terminal 36, the text font data as serial data is inputted fromthe external apparatus storing the title characters. The data representstitle characters using a plurality of dots. The data represent acharacter as a set of dots by designating each dot as "on" or "off". Thedata is prepared as a digital signal in advance.

The text font data is inputted to the display data converting circuit 40through the serial I/O 38. The display data converting circuit 40calculates the addresses in the memory 24 for storing each bit of thetext font data and outputs the address signals. Meanwhile, the text fontdata is inputted to the shift register 16 and converted to the paralleldata of, for example, 8 bits. The converted text font data is stored inthe memory 24 in accordance with the addresses designated by the displaydata converting circuit 40. On this occasion, the display dataconverting circuit 40 serves to restructure the original titlecharacters from the inputted text font data and convert theconfiguration of the restructured characters.

In general, a compact electronic organizer or the like is capable ofdisplaying a limited number of characters at a time. Because there is noneed in particular in such devices to express characters with highfineness, the number of dots forming each character is not so large. Asan example, an apparatus representing one character with 16×16 dots on aliquid crystal display of 64 dots high and 96 dots wide is commerciallyavailable. In this electronic organizer, each line forming a characterhas a width equivalent to one dot.

On the other hand, the superimposed picture is supposed to be reproducedin a home television set. In case of the home television set, the numberof dots which can be displayed on a picture frame is considered to be,for example, 192×192 dots or 256×256 dots.

Accordingly, when the title data inputted from the terminal 36 is storedas it is in the memory 24 and superimposed on the video signal, thebalance of the reproduced title character with respect to the reproducedpicture is significantly deteriorated. The deterioration is caused, forexample, because each character of the title is far smaller than thepicture frame, each character is so close to each other that an areaoccupied by the title is very small with respect to a television pictureframe.

Therefore, in storing the text font data in the memory 24, the characterdata converting circuit 40 processes the text font data as follows. FIG.3 is a schematic diagram of a title block showing a principle of theprocessing. Referring to FIG. 3, the title block in which characters of16×16 dots are arranged in 4 rows and 6 columns is expanded into a blockof 192×192 dots by the display data converting circuit 40. On thisoccasion, each character is converted from a display by 16 ×16 dots intoa display by 32×32 dots. At the same time, a blank row having a width of16 dots is formed between the respective rows. The title characters areprocessed in this way and stored in the memory 24.

The above-described processing for the text font data is carried out bythe display data converting circuit 40. A block of 64×96 dots can beconverted into a block of 192×192 dots by making one dot of the inputtedtext font data to correspond with adjacent 4 dots in the memory 24. Thiscorrespondence can be determined as a unique one. A desired convertingoperation can be implemented by making the correspondence into a tableto store the same in the ROM or the like and searching the table inaccordance with a program.

As the foregoing, the text font data inputted from the terminal 36 isconverted into a preferred form for a title by the display dataconverting circuit 40 and stored in the memory 24. The text font datahas been previously prepared as the digital data by the external device.Therefore, the title character portion and the background are clearlydistinguished from each other in the title stored in the memory 24. Inaddition, an electronic organizer and the like are capable of preparinga plurality of titles to be stored therein, and therefore, a title canbe converted into video signals far more easily than by a conventionalapparatus for which a title is created by hand-writing each time.

FIG. 4 is a block diagram showing a schematic structure of anotherembodiment of a superimposing apparatus according to the presentinvention. Referring to FIG. 4, the superimposing apparatus differs fromthe superimposing apparatus shown in FIG. 2 in that it includes acontroller 42 connected to the serial I/O 38 and avertical-line-thickening circuit 44 for increasing width of verticallines connected to the controller 42 and the memory 24 instead of thedisplay data converting circuit 40. The controller 42 serves as thedisplay data converting circuit 40 in FIG. 2 to restructure the textfont data to be inputted and twice enlarge the same. The circuit 44 isfor thickening the vertical lines of the title characters stored in thememory 24.

The pictures superimposed by the apparatus is supposed to be recorded ona VTR. It is a common practice that the picture is reproduced by a hometelevision set and displayed thereon not by a personal computer and thelike. The home television set displays color pictures by means ofso-called composite video signals. A bandwidth of a color signal forrepresenting colors in the composite video signal is no more than theorder of 500 KHz. Therefore, color resolution of the home television setin a horizontal direction is low.

Each line of the character twice enlarged by the superimposing apparatusshown in FIG. 2 has a thickness of about two dots. With such a smallthickness, the colors, particularly of the vertical lines are thin orare difficult to be taken on due to the low color resolution of the hometelevision set in the horizontal direction.

The circuit 44 is provided for thickening the vertical lines in order toimprove reproduced picture quality. Referring to FIG. 4, the circuit 44includes a shift register 50 connected to the controller 42, a shiftregister 46 connected to the controller 42 and the shift register 50, aone-bit register 48 connected to the controller 42 and the shiftregister 46, an OR circuit 52 having two inputs connected to the outputsof the shift register 46 and the shift register 50 respectively, and ashift register 54 connected to the OR circuit 52 and the memory 24 forconverting serial data into parallel data and for inputting theconverted parallel data into the memory 24.

A basic operation of the superimposing apparatus shown in FIG. 4 is thesame as that of the apparatus according to the first embodiment shown inFIG. 2. This apparatus operates in three operation modes of a firsttitle-image storing mode, a second title-image storing mode and asuperimposing mode. The operations of the apparatus in the firsttitle-image storing mode and the superimposing mode are the same asthose of the conventional apparatus and the apparatus according to thefirst embodiment, and therefore description thereof will not be repeatedhere. Only the second title-image storing mode will be described in thefollowing.

In the second title-image storing mode, text font data of a titleprepared by an electronic organizer, a word processor or the like istransferred to the superimposing apparatus through the terminal 36. Thetext font data is inputted to the controller 42 through the serial I/O38. The controller 42 restructures an original character image from theinputted text font data and twice enlarge the text font data. FIG. 5Ashows the font data before being twice enlarged. FIG. 5B is a schematicdiagram of a matrix showing a character represented by the text fontdata which is twice enlarged by the controller 42. A square on thebottom left-hand corner of FIG. 5A shows a unit storage cell 104corresponding to one dot of the text font data. Four squares on thebottom left-hand corner of FIG. 5B show 4 dots expanded from one dot inFIG. 5A. The four dots constitute a unit storage block representing oneunit dot of the expanded image.

In the text font data outputted front the controller 42, each line whichpreviously had a thickness of one dot has a thickness of 2 dots. Athickness of vertical lines of the text font data is increased by onedot by the circuit 44 and stored in a predetermined address of thememory 24. FIG. 5C shows a title character with vertical lines increasedin thickness by one dot. In FIG. 5C, the portions hatched withleft-downward lines are those added by the circuit 44.

An operation of each element of the circuit 44 is as follows. One row ofthe text font data twice enlarged by the controller 42 isparallel-loaded into the shift register 46 and the shift register 50.The shift register 46 shifts all the stored bits by one bit to the rightin response to the shift clock from the controller 42. On this occasion,the rightmost one bit of the shift register 46 is stored in the one-bitregister 48. The one bit stored in the register 48 goes to the mostsignificant (leftmost) bit of the shift register 46 and set when all thebits are shifted rightward in a processing of the next characters.

The above-described rightward shifting is carried out only for the shiftregister 46. After the processing of the rightward shifting, the shiftregisters 46 and 50 sequentially shift the stored contents leftward inresponse to the shift clock from the controller 42. As a result of theleftward shifting, the serial data representing the text font data isoutputted from the shift registers 46 and 50. Signals outputted from theshift register 46 are equivalent to those obtained by delaying thesignals outputted from the shift register 50 by one bit.

The OR gate 52 takes a logical OR of a signal from the shift register 46and a signal from the shift register 50 and inputs the result to theshift register 54. The shift register 54 accesses the memory 24 andwrites the data of a predetermined number (in this embodiment, eight) ofbits as the parallel data into the memory 24. Accordingly, the datastored in the memory 24 takes a configuration twice enlarged from theoriginal character and having vertical lines increased in thickness byone dot. That is, the shift register 46 serves to draw a boundarybetween two types of signals. The OR circuit 52 equalizes the bits onthe right side of the boundary to the bits on the left side, therebyserving to move the boundary rightward by one bit.

As described above, increasing the thickness of vertical linescompensates for the low color resolution of a home television set in ahorizontal direction compared with the first embodiment. If an imagewhich is superimposed with this apparatus is reproduced and recorded bya VTR, the superimposed title is clear, well balanced, and further moretakes on adequate colors.

The present invention is not limited to the above-described embodiments.For example, in the above-descrived embodiments, text font data preparedby an external apparatus such as an electronic organizer or a wordprocessor and generated by a character generator provided therein isinputted to the superimposing apparatus. However, the present inventionis not limited to such a system. For example, the superimposingapparatus may self-contain a character generator and may receiveexternally supplied character codes, thereby generating text front datacorresponding to the character codes by the character generator.Furthermore, another apparatus may be provided which includes akey-board and a character generator to prepare a title by using amonitor in a built-in-camera VTR or the like with the superimposingapparatus. In addition, it goes without saying that the same effect canbe obtained with an apparatus which includes other memory fortemporarily storing text font data, converts the stored contents intovarious formats in accordance with the specification of an operator andwrites the converted data into a superimposing memory. Similarly,conversion of the characters is not limited to a double-size expansion,but other conversion may be performed in the range of the numbers ofcharacters permitted. The amount of rightward shifting of each bit ofthe shift register 46 is not limited to one bit. As long as a characterto be displayed is correctly distinguished, it may be shifted by aplurality of bits.

Although the present invention has been described and illustrated indetail, it is clearly understood that the same is by way of illustrationand example only and is not to be taken by way of limitation, the spiritand scope of the present invention being limited only by the terms ofthe appended claims.

What is claimed is:
 1. A superimposing apparatus for superimposing apredetermined image signal on a video signal to form a superimposingvideo signal, comprising:inputting means for inputting a binary signalincluding a first predetermined plurality of bit information having apredetermined order; storing means for storing said binary signal andhaving an arrangement of at least a first plurality of storage blocks;each of said first plurality of storage blocks including an arrangementof a second plurality of unit storage cells, each of the secondplurality of unit storage cells for storing one bit of said firstpredetermined plurality of bit information; storage block selectingmeans, responsive to said inputted bit information, for selecting one ofsaid first plurality of storage blocks based on said predetermined orderto store each one bit of said inputted bit information in all of saidunit storage cells included in the arrangement of said one selectedstorage block; and signal switching means for sequentially reading saidbit information stored in said unit storage cells in synchronizationwith said video signal, in a predetermined order, to selectively switchbetween said video signal and the predetermined superimposing videosignal and output the selectively switched video singal andpredetermined superimposing video signal in response to said bitinformation read by said signal switching means.
 2. The superimposingapparatus as claimed in claim 1, wherein each of said storage blockscomprises said second plurality of unit storage cells arranged so as tologically form a predetermined matrix.
 3. The superimposing apparatus asclaimed in claim 2, wherein said matrix is divided into a thirdplurality of rows arranged in a first predetermined direction, each ofsaid third plurality of rows comprising a fourth plurality of unitstorage cells arranged in a second direction intersecting said firstdirection.
 4. The superimposing apparatus as claimed in claim 3, whereina product of said third plurality and said fourth plurality isequivalent to said second plurality.
 5. The superimposing apparatus asclaimed in claim 4, wherein said third plurality is equivalent to saidfourth plurality.
 6. The superimposing apparatus as claimed in claim 4,wherein said third plurality is two.
 7. The superimposing apparatus asclaimed in claim 4, wherein two of said unit storage cells adjacent toeach other along said first direction and having different storageinformation form a boundary along said second direction and wherein saidsuperimposing apparatus further comprising:boundary detecting means fordetecting said boundary for every row; and boundary shifting means forshifting said detected boundary toward said first direction.
 8. Thesuperimposing apparatus as claimed in claim 7, wherein said boundarydetecting means detects said boundary only when said bit informationstored in said unit storage cells adjacent to said boundary which isupstream with respect to said first direction is a first predeterminedvalue.
 9. The superimposing apparatus as claimed in claim 8, whereinsaid signal switching means outputs said predetermined superimposingvideo signal when said bit information read by said signal switchingmeans has said first predetermined value and outputs said video signalwhen said bit information read by said signal switching means has asecond value different from said first predetermined value.